The pouring spouts of liquid containers are normally intended to provide a smooth flow of liquid through the spout and also to minimize dripping from the spout at the end of the pouring operation. The drips that form on a spout after pouring are undesirable for numerous reasons including wetting and staining of the exterior of the spout and the container, and often wetting or staining of the surface on which the container rests.
Numerous attempts have been made to provide a dripless spout, and it has been generally realized that providing the spout with a thin or sharply cut off lip may enhance the "dripless" characteristics of the spout. This is recognized in U.S. Pat. No. 2,704,170 to Ray, which describes a teapot formed of ceramic material or glass. The spout opening of the teapot is bordered on the sides and bottom by a spout which extends outwardly and curves downwardly. The spout decreases in cross-section towards its extremity and terminates in a relatively sharply defined U-shaped lip undercut or relieved at its backside. U.S. Pat. No. 3,549,062 to Teetor discloses a pouring vessel provided with a droplet retaining structure which retains the droplet normally formed when pouring on a drip retaining lip. The lip is located at the outside of the sidewall at the front of the vessel and slightly below a pouring portion of the sidewall. The lip defines a small recess or pocket between the lip and a pouring portion of the sidewall. The front portion of the lip has a sharp upper edge with the generally vertical outer face and a very restricted horizontal surface. The lip defines a recess of restricted volume whereby the retaining forces, such as surface tension and cohesive and adhesive forces over the liquid, temporarily retain the last drop of liquid in the recess. This drop then flows through a vertical slot in the pouring portion of vessel and runs back into the vessel.